[sYc]

Marlin, may have been water, but, if you run alky, or even gas can do it, if enough gets in there, and left to sit. These motors will always have a certain amount of blowby, the really good ones making power are “loose”, which means more blowby, which contaminates the oil. At the track the ones that smoked a tad uauslly were the ones making power. On the go karts, we changed the oil between races. I would think you could get by with a day of drag racing without changing the oil but I would definitely change after each day of running.

Per oil, do not run any more then you have to, as the dipper going through the oil costs HP. You want just enough for the dipper “slinger” to pick it up. I carried 6 pre-measured small drink bottles with the right amount of oil in each for a quick change at the track. Some use the low friction oil additives, coconut oil is good as an additive, as heat will not hurt it.

As you discovered, the Briggs does not use a bearing between the rod and crank, therefore clearance is very important. With rods being aluminum and cranks steel, the rods wear, actually get out of round, I found out the hard way (the rod breaks and goes through the block), the cranks get out of round as well. We would mike both during rebuilds, which we did quite often. Gaskets, rods, pistons, valves and valve springs, and rings are relative inexpensive, cranks and cams not so much. Also, I would say your crank bearing(s) a IC block has two, one on the side of the block and one on the side cover, are toast as well.

There are several cam choices, coupled with the headers, moves the power band around.

With the right tools, these motor can be rebuilt in a couple of hours. Really simple design.